Why produce weapons that are effectively unusable?
Ever since the invention of nuclear weapons, their possession has been the ultimate measure of a state’s power – or potential power. The capitalist ruling class, through its state machine (financed by taxing the people), has always armed itself to defend its interests. That does not mean the security and well-being of the population, but the wealth and power of the ruling class, their territory and sphere of influence. Nukes are the ultimate weapon, so the capitalist powers accumulate nukes. Any one of the major powers has enough to wipe out humanity several times over, but the stockpiling goes on and on.